Method for texturing synthetic polymer filaments



NOV. 5, 1968 'i R, C)I BRYANT ET AL 3,408,717

METHOD FOR TEXTURING SYNTHETIC POLYMER FILAMENTS Filed Jan. 19, 1966 2 Sheets-Sheet l 2/0 lul" l /I4 /7 f l, l

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METHOD FOR TEXTURING SYNTHETIC POLYMER FILAMENTS Filed Jan. 19, 1966 2 Sheets-*Sheet 2 /m/@n/Ors Rona/a 0 Bryn/vf Dare/r Wf/vom United States Patent y)A ABSTRACT oF THE DISCLOSURE Undrawn synthetic polymerkfilaments are deformed under controlled pressure whileV being drawn to molecularly orient the same.

This invention relates to an improved method and apparatus for texturing synthetic polymer filaments. More particularly, the invention is directed to a unique and the other gear.

improved method of drawing and crimping syntheticpolymer filaments utilizing a novel gear crimping apparatus. Synthetic polymer filaments, .especially synthetic linear polymeric filaments such as those of polyamide, polyester and polypropylene material, are extruded in an undrawn straight condition normally by melt spinning. Subsequent processes of drawing and crimping may then be carried out on the as-spun filaments to orient -their molecules and to cause the filaments permanently to adopt fa non-linear form when such is the form that is desired. l

Such subsequent processes of drawing `and crimping may be themselves distinct processes, or they may be combined in one distinct process, subsequent to that of extrusion. Alternatively, both the drawing and the crimping may be carried out on the filaments immediately after extrusion and beforeuthey' have been wound up. y

One way of combining the drawing and crimping processes which has previously been proposed is to impart the drawing tension directly by two meshing toothed-,wheel members, so that the filaments are forced into a corrugated shape immediately after they have been drawn. out into the molecularly-oriented state. The` filaments are preferably led several times yround one of the toothedwheel members and a separator means therefor, so as -to make a number of passes between the two members. In another known process, already drawn filaments are crimped by passing them between intermeshing toothedwheel members, preferably heated ones. Y

A further method for simultaneous drawing and crimping is described in British Patent 984,922. In this process, undrawn synthetic polymer filaments are heated and pulled under tension to pass once only between fixed intermeshing toothed-wheel members, one positivelydriven and the other turned by the intermeshing of thedriven toothed-wheel member, to follow a sharply zig-zag path, the tension so imparted being such that the filaments are molecularly oriented, whereby the filaments are caused to adopt a permanently corrugated shape or crimp.

Each of the above described methods utilize crimping gears or intermeshing tooth-wheel members which have been mounted on shafts which were spatially fixed with reference to each other. This arrangement, while being satisfactory from the point of view of making a reasonable product, required a very high degree of accuracy in constructing the various parts ofthe mounting equipment and gears. For example, it is necessary to align the gear shafts parallel to within 0.03 degrees of `arc and the be'arings for the shafts are not permitted to wear to an extent greater than this before replacement is necessary. Using the fixed mounting of gears, the perimeter of the gears have to be free of eccentricity when rotated on the shaft.

3,408,717 Patented Nov. 5, v19H68 Maximum eccentricity allowable in some cases is 0.0002 inch which is exceptionally difficult `to attain. Furthermore, fixed gears are set on the mounting to give a definite intermesh of the teeth, measurable by the distance which the tooth of one gear penetrates the gap between teeth in The amount of crimp developed in the yarn is critically dependent on this intermesh. Too little intermesh reduces crimp, too much causes breakage in the yarn. There is considerable difficulty in setting this intermesh due to the normal inaccuracies inherent in making gears and their mountings.

According to the invention described herein, manyof thek disadvantages asset forth above are avoided. The process 4and Iapparatus as set forth in this specification pro'- vides significant improvements in the crimp properties of the yarn treated. At the same time the apparatus as described avoids the extreme accuracies in the manufacture of gears and their mounting normally associated lwith gear crimping techniques to provide the improved crimped product. f f The processing technique involves the drawing and crimping of synthetic polymer filaments in which undrawn synthetic polymer filaments are heated and pulled under tension to pass once only between means causing the filaments to follow a sharply zig-zag path. The tension imparted is of such quantity that the filaments vare molecularly oriented causing the filaments to adopt a permanently corrugated shape or crimp. The improvements of this invention are attained Iby utilizing a pair of gear wheels as the means for causing the filaments to follow a sharply zigezag path wherein the first gear wheel is positively driven and the second gear wheel is driven by its intermesh of the positively driven first gear. Furthermore, the second gear is movable within the intermesh of the first gear to provide and maintain a controlled pressure of the second gear for intermesh with the first gear. The advantages of the present invention will become more apparent from the detailed description as set forth herein and the accompanying drawings.

In the drawings: FIGURE 1 is an elevational view of the yarn crimping apparatus of this invention, with front wall'broken away. FIGURE 2 is a plan View of FIGURE l. 1 FIGURE 3 is a schematic View with principal parts in locating and illustrating an operative embodiment of the process and apparatus of the invention. Referring to FIGURES 1 and 2 of the drawings, an embodiment of the yarn crimping apparatus includes a frame 10 surrounding the intermeshing gear wheels 11 and 12. The frame 10 contains a slot 13 at the intermesh of gear wheels 11 and 12 for Stringing up yarn to the crimping apparatus. Gear wheel 11 is positively driven by means such as a motor not shown and is mounted on a! rotatable drive shaft 14 attached to fixed bearings 15 and 16 attached to brackets 10a and 10b. Gear wheel 12 which is driven only Iby the cooperation and intermesh of gear wheel 11 is mounted on a rotatable drive shaft 17 supported on movable bearings 18 and 19 within rectangular slots 20a and 20th located within brackets 10c and 10d. Yoke 21 is attached at its open ends 21a and 2lb to bearings 18 and 19 on shaft 17. The shape of yoke 21 is not necessarily critical and can be in the shape of a V, U, Y or other suitable shapes. A resilient means such as a compression spring 22 is located between the yoke 21 at the end opposite to the open end of the yoke 21 and set screw 23 in such a manner to provide a controlled pressure of gear wheel 12 for intermesh with gear wheel 11. As shown in the drawings, a suitable adjustment means such as a tightening screw 23 can be utilized to control the pres-l sure of gear 12 toward gear 11. The resilient means is not limited to a spring but also can include a pneumatic piston or other means to accomplish the same purpose.

` FIGURE 3 is a schematic view of the processing technique Dlocating and illustrating 'the the process with the yarn crimping apparatus. The undrawn filaments 30 such a's polyhexamethylene adipamide in the form of yarn are withdrawn over one end of the supply package 31 through a pigtail guide 32 by means of feed roll 33 and separator roll 34. The yarn is then drawn within the span between feed roll 33 and draw roll 35 with separator roll 36. Within this span is also situated an electrically heated snubbing pin 37 around which the yarn is wrapped -by at least one turn. Between the snubbing pin 37 and the draw roll 35, the yarn is pulled between wheel gears 11 and 12, gear 11 driven and fixed while gear 12 is driven by intermesh of gear 11 as set forth in FIGURES 1 and 2. The speed of the driven gear 11 is such that the yarn speed through the gear wheels is less than the surface speed of draw roll 35. On departure from draw roll 35 and its separator roll 36, the yarn 30a, now fully drawn, is wound on a ring spindle package 38, twist being inserted in the yarn below the balloon-guide 39, by virtue of the rotation of the spindle and of the rotating traveller 41 around ring 40.

The unique feature of the apparatus of this invention is the technique of enmeshing the gears by exerting a controlled pressure to the first gear forcing it into mesh with the second gear. This feature is advantageoues in providing greater crimp retraction at lower tensions than the utilization of fixed enmeshed gears. The frequency of the crimp of the yarn passed through lthe apparatus can be adjusted by altering the number of teeth per inch of the gears and the amplitude altered by increasing or decreasing the pressure of the meshing engagement of the teeth. y

In the process of the invention, the filaments are pulled between the teeth of the toothed-wheel or gear wheel members under tension. This technique has two main advantages. Firstly, the crimp imparted to the filaments is greatly enhanced compared with those processes utilizing fixed gears, or compared to those processes in which the toothed-wheel members alone impart the whole drawing tension or in which already drawn filaments are passed between toothed-wheel members. The second advantage relates to the method of controlling the pressure of one of the gear crimpers. Under fixed conditions the gears cannot adjust to any variations of total denier of the yarn bundle while the present crimping arrangement can provide substantially the same pressure even if a small amount of slubbing of the yarn occurs.

The size of the gear wheels which can be used herein can vary. Normally, gears in the range of 1 to 8 inches in diameter can be utilized having from about 40 teeth'per inch for crimping light, heavy, and medium denier multifilament yarns.

It is highly advantageous to useY involute teeth for the gears as this shape allows more easily for the driving of one gear by the other with a smooth transmission of rotary motion.A Thus, the mechanical problems are greatly eased, as the drive has only to be to -one gear and there is no requirement for matching the rotary speeds of the two gears.

The teeth of the gears may be regular in size and spacing around the gear. If novelty effects are required, the spacing may be irregular or the amplitude of the teeth may be varied around the gear. The yarn may be led directly to the meshing area of the gears or it may be led so as to make a partial wra'p around the periphery of one gear before entering the meshing area.

The temperature of the yarn to be crimped can range from about 100 C. to about 200 C., however temperatures must be maintained below the softening point of the polymer composition of the filaments. The temperature of the heating means such as the'snubbin'g pin will normally have to be slightly higher than the desired yarn temperature at crimping.

6 to about principal"'parts'used in4 4,l The following example will serve to illustrate the process of the invention without limiting the same:

Example As shown in FIGURE 3 of the drawing, a yarn spun from polyhexamethylene adipamide of undrawn denier 220, and containing 17 filaments was fed to the heated snubber pin (180 C.) at 700 pin, the yarn passed through the nip ofthe crimping gears (3 inches in diameter), the gears rotating at 1800 revolutions per minute. Two types of crimping gears were used. One type is set forth in FIGURES 1 and 2 wherein the pressure of the crimping gear 12 is maintained at 12 pounds per square inch and the second type of gears were both fixed in the same enmeshing position as the crimping gears represented in FIGURES 1 and 2. The yarn passed to the drawroll rotating at 2000 feet per minute and thence to a ring and. traveller wind-up.

The following comparison between the fixed gears 4and gears of the apparatus of the invention is made.

feet per minute. From the Gears of the The percent retraction of the yarn is significantly improved utilizing the gears of the present invention. When the gear speed is decreased to about 1700 revolutions per minute, in the case of the gears of the present invention, the tension rises to 20 grams and crimp retraction increases to 40 percent while in the case of the fixed gears, the tension becomes too high at the reduced -gear speed causing a reduction in crimp level and excessive yarn breakage.

It is to be understood that the foregoing description is merely illustrative of preferred embodiments of the invention of which many variations may be made by those skilled in the art within the scope of the following claims -without departing from the spirit thereof.

What is claimed is:

Y1. In a process for drawing and crimping synthetic 'polymer filaments in which undrawn synthetic polymer filaments are positively advanced from a supply thereof, heated, subjected to a drawing tension, deformed in a zig-zag manner while under said drawingtesion and while simultaneously imparting a component of motionin the mean direction of travel of the filament, and are pulled under tension after being deformed, the improvement comprising deforming the filaments under a substantially constant positive pressure `while maintaining the filament under a positive tension in a direction away from the deforming zone.

2. The process of claim 1 in whichthe filaments are heated to a temperaure in the range from about C. to about 200 C. v

3. The process of claim 1 wherein the synthetic polymer filaments are polyhexamethylene adipamide.

References Cited UNITED STATES' PATENTS 2,311,174 2/1943 Hitt 28--72 2,758,357 8/1956 Goodhue 28-1 3,116,531 1/1964 Hills et al. 28-1 3,197,837 8/1965 Hills et al. 28-1 3,293,843 12/ 1966 Bibby et al 2'8--1 3,325,987 6/1967 Hollihan et al. 28-72 X LOUIS K. RIMRODT, Primary Examiner. 

